Projector



sept. 29 1942 R. v. BRosT ETAL 2,297 532 PROJECTOR Filed March 9,l 1940 ll Sheets-Sheet l gl i I I I Lu n n 'llllmll l I miIIIIIIHIIHIHIIIHIIII H111 IH Sept. 29, 1942.y R. v. BROS-r ETAL PROJECTOR Filed March 9, 1940 ll Sheet'S-Sheet 2 Vllllil..

sept. 29, 1942.

` R. .V. BROST ET AL.

PROJEGTOR Filed March 9, 1940 11 Smets-sheet s 155 I gllll Sept 29, ,1942. R. v. BRosT ETAL 2,297,532

PROJECTOR Fil'ed March 9. 1940 l1 Sheets-Sheet 4 Sept' 29, 1942- R. v. BROS-r ETAL. 2,297,532

PROJECTOR Filed March 9, 1940 11 sheets-sheet s Sept. 29, 1942. R. v. BRoST ETA 2,297,532

PROJECTOR Filed March 9, 1940 l1 Sheets-Sheet 6 Sept. 29, 1942. R. v. BRosT x-:TAL

PROJECTOR V Filed March 9, 1940 ll. Sheets-Sheet '7 Sept 29 1942- R. v. BRosT ETAL 2,297,532

PROJECTOR Filed March 9, 1940 ll SheetS--Sheetl 8 'Sept 29, 1942. R. v` BRosT ErAL 2,297,532Y

PROJECTOR Filed March 9, 1940 1l Sheets--Sheetl 9 Sept- 29, 1942- R. v. BRos-r ETAL 2,297,532

PROJECTOR Filed March 9, 1940 l1 Sheets-Sheet l0 lo JF" 7. `\ZO 105 15a ,55 131 i 1011l i "O 103 'Y 1l Sheets-She'et l1 "mill" I l PROJECTOR mi m@ R. V. BROST 'Elf AL Filed March 9, 1940 Sept. 29, 1942.

vs I.

Patented Sept. 29, 1942 PROJECTOR Robert V. Brostl and Carl K. Schwartz, Elkhart Lake, Wis., assignors to Adolph L. Langenfeld,

New Holstein, Wis.

Application VMarch 9, 1940," Serial No. 323,132

17 Claims.

This invention relates to projectors, and refers particularly to the stereopticon type of projector used for the projection of still pictures.

While this invention contemplates improvementsin projectors generally, it is particularly scribed wherein the two images or slides of each set are rmly held against relative displacement concerned with the provision of a projector designed Lfor the projection of three dimension pictures.

Three dimension photographyv is not new, but heretofore, no practical means has ever been devised for fully utilizing its advantages.

As is well known to those skilled in the art. in three dimension photography, the picture is taken from two points. by means of two coordinated cameras, the camera locations corresponding to the two leyes of an observer. The depth of natural observation is thus transferred to the two pictorial images so thatv with the proper. mechanism, it is possible to reproduce the picture in all its natural beauty.

Heretofore, however, there has been no practical device by which this reproduction could be effected.

It is, therefore, a primary object of thisv invention to provide a projector `by which three dimension pictures can be projected upon an appropriate screen to restore all the natural depth and beauty of the original subject to an observer equipped with a proper pair of glasses or spectacles.

In carrying this invention into effect, polarized light is utilized. In other words, one of the two pictures is projected by light polarized in one direction, while the other picture is projected by light polarized in a diametrically opposite Y direction.

To this end "Polaroid lenses are used in the projector, and observers are equipped with glasses or spectacles, the lenses of which are likewise made of Polaroid One of the prerequisites of successful three dimension projection is that the images which may be in the form of conventional lantern slides or which may be mounted on appropriate rolls of lm, must be held accurately against relative displacement and in proper position with relation to the focal axes.

If the slides or images are permitted even the slightest degree of relative displacement, that is,

if one is permitted to move out of its proper position with relation to the other, the projected images will be distorted in a manner resulting in severe eye strain. e

It is, therefore, a further object of this invention to provide a projector of the character deduring their projection and wherein the two images or slides move in unison to and from projecting positions.

Because of their excellence of the reproduction and their retention of all the natural beauty and depth, three dimension pictures and the projector of this invention are particularly useful and advantageous to lecturers and as mediums of education. j

The projector of this invention is also very useful for advertising and sales promotion and in other fields wherethe sharpness and clarity of detail achieved with threedimensicn pictures is important.

Another object o this invention is to provide means whereby an entire series of slides or images can -be automatically shown without necessitating manual handling of the slides. This precludes'the possibility of inverted projection and other objectionable results inevitable where the projector is tended manually.

Another object of this invention resides in the provision of means whereby a series 'of slides kmay be shown automatically* vin a regular successive sequence, or at the dictation of an operator stationed remotely from the machine.

To further simplify the handling of the slides, the present invention has, as another of its objects, the provision of. means whereby entire magazines or cartridges of slides or images may be quickly bodily inserted and removed from the machine.

Further, in the interest of accuracy, it is another object of this invention to provide mechanism whereby the slides or images are automatically taken out ofl their magazine or cartridge, properly positioned for` projection, and returned to the magazine or cartridge in their proper respective locations.

In connectionwith the manner in which the slides or images are handled, it is another object of this invention to so arrange the slides or images in open-topped trays that automatically driven elevators may lift the slides or images simultaneously' from the trays into proper projecting position.

Another object of this invention is yto provide means whereby the lifting of one set of slides into projecting position releases a shown set of slides for return to the magazine.

lof a series of slides or images, the entire procedure is repeated by first restoring the movable magazine or cartridge to its initial position and then resuming its intermittent advance to successively bring the sets of slides or images into position for projection.

In this connection, it is another object of this invention to provide means which may be readily adjusted to effect return of the slide magazine or cartridge after any number of slides or images within the capacity of the machine have been shown.

While the projector of this invention is designed primarily for the projection of three dimension pictures, it is also contemplated that when desired, it may be used for automatic projection of the conventional picture slides.

Another object of this invention directed toward ease of operation resides in the provision of an improved manner of mounting the projection lenses, which enables the same to be lifted out as a unit to afford ready access to the slide magazine.

In this connection, it is another object of the present invention to provide means for simultaneously adjusting the projection lenses transversely with relation to each other.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims. The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which;

Figure 1 is a perspective view of a projector embodying this invention;

Figure 1a is a diagrammatic view illustrating the manner in which three dimension projection is effected by the projector of this invention;

Figure 2 is a vertical sectional view through the projector on a plane indicated generally by the line 2-2 in Figure 1;

Figure 3 is a horizontal sectional view through the machine taken on a plane between the mechanism base and the bottom of the magazine supporting carriage and looking down on top of the mechanism base;

Figure 4 is a perspective view of the underside of the movable magazine supporting carriage;

Figure 5 is a perspective view showing the top of the mechanism base and the mechanism mounted thereon;

Figure 6 is a horizontal sectional View through the machine on a horizontal plane directly above the magazine carriage with parts broken away and in section to illustrate structural details;

Figure 7 is a' detail perspective view taken through Figure 6 on the plane of the line 1 1;

Figure 8 is a detail view in side elevation of the pawl and ratchet mechanism for intermittently advancing the carriage;

Figure 9 is a view similar to Figure 8 but show- Figure 11 is -a perspective view of the mechanism by which the last set of slides is released upon actuation of the trip which initiates the functioning of the carriage return mechanism;

Figure 12 is a detail sectional view through the drive mechanism taken generally on the plane of the line I2-Il2 in Figure 3;

Figure 13 is a front view of the two lense units illustrating the manner in which their adjustments are quickly and simultaneously effected;

Figure 14 is a detail sectional view through the lower fore part of the slide magazine and the mechanism directly associated with the elevators by which the slides are lifted from the magazine into projecting positions;

Figure 15 is a view similar to Figure 14 but showing the carriage advanced and the elevators about to lift a set of slides;

Figure 16 is a view similar to Figures 14 and 15 but showing the parts in their positions during the actual lifting of the slides;

Figure 17 is a vertical sectional view through the slide holder or receptacle illustrating a slide in position and another about to be raised to projecting position;

Figure 18 is a view similar to Figure 17 but showing the manner in which the slide holder is ing the parts in their operative advancing posi-v tions; y'

Fig-ure 10 is a fragmentary detail view illustrating a lost motion connection between the carriage return rack and the carriage which assures complete descent of the last shown set of slides before carriage return begins;

tripped by the rising slide to release the shown slide;

' Figure 19 is a horizontal section view through the slide receptacle to illustrate the manner in which the mechanism illustrated in Figure 11 functions to trip and release the last shown set of slides; and

Figure 20 is a vertical sectional view through the machine directly in front of the slide receptacle showing a set of slides in position.

Referring now particularly to the accompanying drawings, in which like numerals indicate like parts throughout the several views, the numeral 5 designa-tes generally the supporting stand or base of the projector which may be of any suitable design and construction; and in the present instance comprises a rear leg unit 6 havt ing spaced uprights 1 connected to an adjustable front leg 8 by a subbase 9.

Above the subbase 9 is a mechanism base II which is rigidly connected with the leg structure by, a substantially U-shaped bracket. I2 fixed to the adjustable front leg and by longitudinal side rails I3 rigidly connected with the uprights 1 of the rear leg structure and connected with the mechanism base by spacers I 4,

Directly above the side rails I3 Vbut terminating short of the front ends thereof are two upper side rails I5. Upright spacers I6 serve to rigidly tie the upper and lower side' rails `together.

Mounted on the upper side rails I5 near the rear of the machine is a lamp housing I8 within which two light sources L (see Figure 1a) are located. To carry oif vthe heat generated by the lighthsources, an appropriate blower,' indicated generally by the numeral I9, is mounted on the lamp housing. :Phe blast from the lblower is directed downwardly through the lamp housing across the'open front end thereof to carry away the heat .before it reaches the slide receptacle designated generally by the numeral 2| 'by which the light beams are projected onto the same area of an appropriate screen 22.

The projection lenses are readily detachably mounted as a unit by means of rods 23 slidably received in guides 24. The guides 24 are rigidly supported from the upper side rails by legs 25 and the front ends of the rods 23 have a supporting plate or frame indicated generally by the numeral 26 xed thereto. This supporting plate or frame isV appropriately apertured to permit the light rays to pass therethrough and `is equipped with transverse guides in which the lense units are transversely slidably mounted.

As particularly shown in Figure .13, the lense units are simultaneously adjustable transversely toward and from each other by a right and left hand screw threaded adjusting stem 21 held against endwise motion with relation to the plate or frame 26 and threaded in nuts 28 rigid with respect to the lense units. A knurled head 29 on the stem provides means for turning the stem.

Simultaneous longitudinal adjustment of the two lense units is also provided for. This adjustment is effected by -a single rotatable stem 30 carrying gears 3| which mesh with adjusting plnions 32 of the lense units.

Connected with the rear of the plate or fr-ame 26 are two bellows 33, the opposite ends of which are readily detachably connected with the front of the slide receptacle in line with the openings therein.

Hence, by sliding the projection lense unit forwardly until the rods 23 are disengaged from their supporting guides 24 and by lifting the bellows out of their sockets on the front 'wall of the slide receptacle, the entire projection lense unit including the bellows may be removed.

Unrestricted access to the slide receptacle and also to the space-between the side rails along which the slide magazine 34 travels is thus quickly obtained.

The slidable support for the lense unit and front end of the bellows also enables rough focusing, as will -be readily apparent.

The slide magazine, in a broad sense, comprises an open-topped oblong box having end walls 35 connected at the top by tie rods 36 and at the bottom by straps 31. The side walls of the box are formed by a series of vertical angle members 38 arranged with one flange fiat againstthe rods 36 and the straps 31 and with their other flanges in parallel spaced relation to provide spacers. Extending down the center of the 'box are two similar rows of angle members mounted in the same way. Hence, the magazine has two yparallel rows cept for two spaced rails 39 beneath each row of slide pockets, the space between the adjacent rails 39 enabling the ascent of slide elevators 40 by which the slides are lifted from the magazine into projecting positions within the recepta-cle 20. Preferably, these bottom rails 39 are provided with cushion strips 4I of rubber or other suitable material upon which the slides rest.

The entire box-like magazine is readily detachably supported on a carriage indicated generally by the numeral 42. This carriage consists of a frame formed of two side members 43, a center member 44, and angle-shaped cross pieces 45 and 46. l

The outer marginal edges of the side members 43 are slidably received in guideways 41 cut in .The bottom of the box-like magazine is open exmagazine into projecting position foreach cycle the lower side rails I3 so that the carriage is slidable along and between theside rails.

To guard against objectionable play, the movable carriage is held to one side by a gib 48 xed to the adjacent side rail I3 and riding in a groove 49 in the undersurface of the adjacent side member of the carriage.

The box-like kslide magazine is set on the table-like carriage in a manner permitting the same tobe quickly lifted therefrom and another set in its place. The upright flanges of the cross pieces and 46 engage the ends of the magazine and hold it against shifting endwise on the carriage. Lateral shifting of the magazine with respect to the carriage is prevented by the side rails I3 between which the magazine slides.

Through the use of these magazines and the ease with which they may be inserted and removed, individual handling of thel slides is entirely obviated. They need never be taken from their respective magazines; and as will be obvious, one magazine may contain all the slides of .any particular subject or lecture, and the magazines may be used to store the slides.

For three dimension projection, the directly opposite slides in the two adjacent rows constitute a set and represent the two images or pictures taken by the three dimension camera.

If ordinary at pictures are to be shown; one half of the projector may be rendered inoperative by disconnecting its light source. In that event, while two slides will be lifted from the of operation, only one will be projected.

Thus, rst one and then the other row of -slides can be shown. The capacity of the magazine is thus doubled for ordinary flat picture projection.

The carriage is intermittently advanced to bring the sets of slides successively into a predetermined plane which may be generally termed the projection plane in that the slides occupy substantially this plane when in their projecting positions.

The slides occupying this plane ware in position to be lifted by the elevators 40, the operation ofk which is coordinated with the intermittent advance of the carriage. The carriage advancing mechanism, as well as the elevators and all other moving parts, are driven from a motor M mounted on the subbase 9.

The drive from the motor is stepped down by a belt and pulley 50 and 5I and a gear train 52 which includes a continuously driven clutch member 53. 'Ihis clutch member is slidable and rotatable on a transverse shaft 54 journalled in bearings 55, 56 and 51 carried by the mechanism base II. It comprises a gear by which it is vconnected to the gear train and a hub projecting from opposite faces of the gear and having clutch pins 58 and 59 extending from the ends thereof.

These clutch pins are engageable with cooperating clutch pins 60 and 6I, respectively, the clutch pin 60 being carried by the hub of a gear 62 loose on the shaft 54 but held against endwise motion with respect thereto and the pin 6I is carried by a clutch member 63 fixed to the shaft 54.

In the neutral position of the continuously driven clutch member 53, neither set of clutch p-ms is engaged.

A bifurcated lever 64 pivoted to the mechanism base II, as at 65, with its twoarms embracing the gear of the clutch member 53 releasably holds the clutch member in its neutral position by virtue of friction derived from a spring 85 fixed to the bifurcated lever and bearing against a stationary cross piece 51 (see Figure 5).

Upon shifting of the clutch member 59 to the right in Figure 2 to bring about the driving engagement of the clutch pins 59 and 5|, the shaft 54 becomes drivingly connected with the clutch member and is driven thereby to effect the advance of the carriage one step and also effect the functioning of the slide elevators. Such shifting of the clutch member 58 is effected by means of an electromagnet 58 which may be energized at the will of the operator by means of a suitable switch, or automatically in response to the operation of suitable timing mechanism.

Upon energization of the electromagnet, an armature 59 (see Figure 3) is attracted to it to push the clutch member 59 toward the clutch member 53. This effects the engagement of the clutch to drive the shaft 54.

At the outer end of the shaft 54 is a pinion 10 meshing with a rack 1|. The rack is slidable in suitable guides 12 and 18 mounted on the mechanism base II.

A spring 14 connected to the rear end of the rack beyond the adjacent edge of the mechanism base and extending along the underside of the mechanism base to be connected thereto, as at 15, yieldingly holds the rack in its retracted position. Retraction of the rack by the spring is limited by the engagement of a stud 15 which projects from the side of the rack in position to engage the rear edge of the bearing 12.

The stud 15 and a similar stud 11 connect a cam bar 18 to the rack for movement in unison therewith. The front end of this cam bar is connected to the piston rod 19 of a dashpot 80 by which retraction of the connected cam bar -and rack is retarded, the speed` of retraction being dependent upon the size of the bleed hole 8| in the end of the dashpot cylinder. The purposeof retarding retraction will be brought out hereinafter.

'I'he opposite rear end of the cam bar is cut ofi to provide an inclined cam surface 82 by which a pawl actuating bell crank lever 89 is rocked about its pivotal mounting 84. A suitable bracket 85 fixed to the mechanism base provides the pivotal support for the bell crank lever 83, and a spring 85 holds the bell crank lever yieldingly in its retracted position.

One arm of the lever has a roller 81 mounted thereon in position to ride up the cam surface during the operative stroke of the cam bar.

The other arm of the bell crank lever has a pawl 88 medially pivoted thereto. A spring 89 connected between the heel of the pawl and the bell crank lever yieldingly projects the toe of the pawl upwardly for engagement with the teeth of a ratchet bar 90 fixed to the undersurface of the carriage.

When the bell crank level 89 is retracted by its spring 85, it assumes a position at which the pawl is held clear of the ratchet bar by engaging a pin 9| carried by the bracket 55 (see Figure 8).

Upon initial longitudinalrmotion of the rack and cam bar in response to rotation of the pinion 10 in the manner aforesaid, .the pawl mechanism is actuated from its position shown inlliguretitoiirstcausethetoeofthepawl to engage one tooth of the ratchet bar and to thereafter advance the ratchet bar, and consequently, the carriage a predetermined distance.

The height of the inclined cam 82 is such that the distance the carriage is advanced by this mechanism is exactly the amount required to advance the slide magazine the distance necessary to bring the next successive set of slides directly over the elevators.

While the rack and cam bar continue their longitudinal motion after the carriage has been advanced the required amount, the flat top surface of the cam bar merely ridesunder the roller 81 without effecting the position of the pawl mechanism so as not to disturb the location of the carriage and consequently the slide magazine.

As the rack and cam bar are advanced by the pinion 10 a predetermined amount, the end of the rack moves into mesh with a second pinion 92. This pinion 92 is fixed to a shaft 93 journalled in the bearing blocks 55 and 51.

On the shaft 93 and adjacent to the inner faces of the bearings 55 and 51 are pinions 94 and 95 which mesh with racks 95 and 91, respectively, cut into the elevator stems by which the elevators are guided for vertical movement in suitable guideways formed in the bearing blocks 55 and 51.

Inasmuch as the pinions 94 and 95 are fixed to the shaft 98, it follows that the elevators rise in exact synchronism to lift the set of slides in position thereover. Proper timing between the carriage advance and the rise of the elevators is achieved by the spacing between the pinions 10 and 92 in coordination with the angle of the cam surface 82.

As the elevators begin their ascent, they lift the slides in position thereover up from the magazine into the slide receptacle 20. In the slide receptacle, there are two sets of opposed guideways 98. These guideways in the present instance comprise vertical angle members 99 fixed at their lower ends to a transverse angle member |00 the ends of which are secured to the upper side rails I5.

The upper ends of the angle members 99 are connected by an upper transverse member |0|. Projecting from the inner surfaces of the longitudinal flanges of the angle members 99 are guides |02 so positioned that the slides being lifted by the elevators slide over the forward surface thereof. These guides are spaced from the transverse fianges of the angle members 99 a distance sufficient to permit a slide to pass therebetween.

As the slides rise up along the guides |02, the upper edges thereof engage and ride under the inclined lower rear edges |03 of depending pivoted slide holding fingers |04. These fingers are arranged in pairs, two each, with the fingers of each pair fixed to the opposite ends of a tube |05 so that the fingers of each pair are tied together to move in unison.

A single shaft |05 passing through aligned holes in the longitudinal fianges of the angle members 98 pivotally mounts the two pairs of slide holding fingers; and tension springs |01, one for each pair of slide holding fingers yieldingly holds the same in the operative slide holding positions shown in Figure 17.

This position of the slide holding fingers is defined by their engagement with the transverse fianges of the angle members 99. At their engagement with these fianges of the angle members 99, the rear edges of the slide holding fingers are pointed to deiine the inclined edges |03 and slide supporting ledges |08 by which the slides are held in their projecting position, shown in Figure 17.

As a set of slides to be shown is lifted by the elevators, the upper edges of the slides ride under the inclined edges |03 to move the slide holding fingers against their springs |01 to inoperative position releasing the slides just shown for gravitational descent. The descending slides drop by gravity into their respective pockets in the magazine.

The ascending slides are lifted by the elevators to a height above the proper projecting position and until the lower edges of the slides are well above the top of the guides |02. This permits the lifted slides to be pushed back against the transverse flanges of the angle members by the spring propelled motion of the slide holding fmgers in moving to their operative positions, shown in Figure 17. Hence, as the elevators descend, the slides move down onto the, ledges |08 to be held thereby in proper projecting positions.

To hold the slides fiat against the transverse flanges of the angle members 39, each slide holding finger is equipped with a lever |09 pivoted thereto, as at |I0, and yieldingly urged by a light spring I I I against the slide.

Inasmuch as the springs III -are quite light, these levers do not interfere with the proper positioning of the slide holding fingers by their springs |01 and do not'affect the gravitational descent of the shown slides.

It is thus evident that the mechanism just described eifects an automatic transfer` of slides; for as one set of slides is being elevated into projecting position, another set which has just been shown is released and drops back into the magazine.

As pointed out hereinbefore, the ascent of the elevators is effected by rotation of the shaft 93 in response to the advance of the rack 1I. The extent the 'rack is advanced depends upon the duration of the clutch engagement which is established by energization of the electromagnet. Such engagement obtains until the clutch member 53 is moved back to. its neutral position. This is accomplished at the termination of the proper advance o the rack 1| by a cam I I2 fixed to the cam bar 18 and operable to depress a rod I I3 slidably mounted in the guide 12 and a bearing II4.

The rod |I3 is of such length and is so positioned with relation to the bifurcated lever 64 that during engagement of the clutch by the shifting of the clutch member 53 in response to energization of the electromagnet, the rod is pushed into the path of the Cam I |2.

Hence, as this cam moves along with the rack and cam bar, it depresses the rod ||3 to push on the bifurcated lever 64 which in turn carries the clutch member 53 to its neutral position. The clutch having been disengaged, the rack and cam bar are released for retraction by the spring 14.

Retraction of the rack and cam bar effects retrograde rotation of the shaft 93 and consequently descent of the elevators which takes place slowly because of the dashpot action aforementioned to insure quiet operation.

Another function of the advancing rack and cam 1bar is to open and close the circuit of the light sources so that during the transfer of slides both light sources are out. vTo this end, a mercury switch |I5 is pivotally mounted from the underside of the mechanism base to normally occupy a closed position. Y

A lever II6 connected with this switch projects up through an elongated opening in the mechanism base into the path of a pin I|1 movable with the cam bar. As this pin travels along its defined path with the cam bar, it engages the lever II6 to open the switch. The parts are so proportioned that the switch is held open until the rack and cam bar reach substantially their fully retracted positions, at which time complete transfer of slides has been effected,

The cycle just described is repeated everytime the electromagnet is energized; and as stated hereinbefore, energization of the electromagnet may be eiected manually at the will of the operator through closure of an energizing circuit from any remote point, or it may be eifected automatically by means of a suitable switch in the energizing circuit which is closed by any suitable timing mechanism or by some part of the projector mechanism, as for instance, the rack 1I or the cam bar 18.

Each cycle of operation advances the carriage and consequently the slide magazine the proper distance to bring the next successive set of slides directly over` the elevators. This intermittent advance vof the carriage continues until the reversing mechanism now about to be described functions to effect return of thef carriage to its initial position.

Inasmuch as some subjects may not require the full number of slides the magazine is adapted to hold, it is desirable that the time at which the reversing mechanism functions shall be adjustable. This is accomplished by providing the carriage with an adjustable trip ||8. This trip,

'as will be presently'described, is operable to effect the functioning of the reversing mechanism. It consists of a hook-shaped member slidable along a groove II9 in the center carriage bottom member 44.

A clamping screw |20 provides means for clamping the adjustable trip at any point along the length of the carriage and to facilitate set-` ting the same, a scale I2| is delineated upon the upper face of the carriage bottom with which a pointer |22 on part of the clamping mechanism cooperates.

The scale is delineated to represent the number of sets of slides which each magazinejholds. It is thus a simple matter to set the trip for operation after any number of slides within the capacity of the magazine has been shown.

Positioned in the path of the trip II8 is a trigger |23. This trigger is pivoted to the side of a bearing block |24 xed to the mechanism base and-engages in a notch |25 in the side of a spring plunger |26.. The spring plunger is slidable in the' bearing block |24 and is positioned to push against the clutch member 53 upon being projected by its spring |21.

The trigger |23 holds the plunger infcocked position by engaging in the notch |25 so that when the trip I I8 engages the trigger during the last advance of the carriage, the plunger responds to push the clutch member 53 to the left with respect to Figure 3 and eiect engagement of the clutch pins 58 and 80.

Upon such'engagement of the clutch pins 58` land 60, the'pinion 62 begins to revolve with the clutch member 53, Meshing with this pinion 62 is a rack |28 supported from the undersurface of the carriage.

A bracket |29 secured to the undersurface of the carriage has the rack slidably connected to its vertical flange by means of studs |30 xed to the bracket and received "in slots |3| in the xack.

The headed ends of the studs hold the rack against the outer face of the bracket, and a spring |32 having one end connected to the bracket and its other end connected to the rack yieldiiigly holds the rack at one limit of the lost motion in the connection between the rack and the carriage.

The direction in which this lost motion is taken up is such that when the pinion 62 first becomes connected with the clutch member 53 and drives the rack, the lost motion must be first taken up before the carriage beginsto move with the rack.

During this interim, the last shown set of slides is released and drops back into the magazine so that when the carriage begins its return stroke, all of the slides are properly in in the magazine.

To effect the release of the last shown set of slides, a-bell crank lever |33 pivotally mounted at its apex from the mechanism base and having one arm thereof connected as at |34 with the spring plunger is actuated by the spring propelled projection of the plunger.

The other arm of the bell crank lever |33 is in position to bear against the adjacent end of a slidably mounted rod |35. The opposite end of this rod is connected through a medially pivoted lever |36 with a rodv |31 also suitably guided for longitudinal motion.

'I'he forward end of the rod |31 has a cross bar |33 fastened thereto in position to engage pins |39 carried by the inner ones of each set of slide holding lingers. Y

Hence, whenthe spring plunger acts to engage the clutch for return of the carriage, the slide holding fingers are immediately pushed to their inoperative positions shown in Figure 18, releasing the last shown set .of slides for gravitational descent into the magazine. The time required for this release of the last shown set of slides, as stated, does not exceed the time reposition quired to take up the lost motion in the connection between the rack |23 and the carriage.

When the carriage reaches its fully retracted position, a cam |40 on the bottom of the carriage engages a pin |4I' extending up from the bifurcated lever 64 to push the same to its neutral position and carry the clutch member 53 to neutral position, thereby disconnecting the drive to the pinion 62.

As the carriage approaches'its retracted position, another cam |42 supported on the under-A surface thereof engages a shoulder |43 fixed with respect to the spring plunger to cock the same by retracting the plunger against its spring far enough to permit the trigger |23 to engage the notch |25, such engagement of the trigger in the notch being `effected by a light leaf spring |44 which bears against the trigger (see Figure 12).

The interconnected linkage comprising the rods |35 and |31 and the lever |38 is returned to its normal position by the springs |01 which act on the slide holding fingers.

Operation tures and that the spectators have been equipped with the proper Polaroid spectacles, the opretraction of the rack and cam bar, the lighty switch closes so that this rst set of slides is projected on the screen.

If the projector is being operated manually, it remains in this condition until the operator recloses the energizing circuit for the electromagnet whereupon the cycle repeats itself; but this time, in addition to the lifting of the next set of slides into projecting position, the rst set which has been shown is released so that it may drop into its respective pocket in the magazine.

These cycles are continued until all of .the slides which the magazine contains have been shown, at which time the adjustable trip functions to initiate the operation of the carriage return mechanism. k

From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent that this invention provides a projector by which three dimension projection is a practical possibility and by which the slides are automatically changed in a practical eilicient manner so that manual handling of the individual slides is entirely obviated.

It is also apparent that the projector of this invention, while 'designed primarily for use with three dimension slides, is equally useful for the automatic projection of ordinary fiat picture lantern slides.

What we claim as our invention is:

1. In a projector, the combination of: means for producing two separate light beams; means for projecting the two light beams onto th'e same area of an appropriate screen; a plurality of slide units, there being two slides in each unit; a'single carrier constrained to linear motion along a defined path substantially parallel to and spaced from the light beams to receive all the slide units; means on the carrier dening pockets opening toward the light beams for removably holding the slide units in a row with`the slide units in separate planes substantially normal to the light beams and the path of motion of the carrier; drive mechanism for moving the carrier with an intermittent motion along said defined path to successively bring each slide unit on the carrier into a predetermined projection plane normal to the light beams; and slide shifting means for moving slide units in said predetermined projection plane from their pockets into projecting positions with one slide of each unit crossing one of the light beams.

2. In a projector, the combination of: means for producing two separate light beams; means for projecting the two light beams onto the same area of an vappropriate screen; a plurality of slide units, there being two slides in each unit; a single `carrier constrained to linear motion along a defined path substantially parallel to and spaced from the light beams to receive all the slide, units; means on the carrier dening pockets opening toward the light beams for removably holding the slide units in a row with the slide units in separate planes substantially normal to the light beams and the path of motion of the carrier; drive mechanism for moving the carrier with an intermittent motion along said dened path to successively bring each slide unit on the carrier into a predetermined projection plane normal to the light beams; and slide shifting means for moving slide units in said predetermined projection plane out of their pockets with an edgewise translating motion and into projecting positions with o'ne slide of each unit crossing one of the light beams.

3. In a projector, the combination of means for producing two separate light beams; means for projecting the two light beams onto the same area of an appropriate screen; a plurality of slide units, there being two slides in each unit; a single carrier for holding the slide units in a single row substantially parallel to but spaced from the light beams; drive mechanism for moving the slide carrier in the direction of said row of slide units, said drive mechanism advancing the slide carrier in one direction with an intermittent motion to successively carry each slide unit into a predetermined projection plane normal to the light beams and moving the slide carrier uninterruptedly in the opposite direction to retract the same; and slide shifting means synchronized with the drive mechanism so as to be operative during the intervals of rest in the intermittent advance of the carrier and wholly inoperative during the uninterrupted retraction of the carrier, said slide`shifting means being operable on edge portions of slide units in said predetermined projection plane for moving said slide units into proper projecting positions with one slide of each unit positioned across one light k beam as each slide unit is brought to said plane bythe carrier.

4. In a projector, the combination of: means for producing two separate lightbeams; means vfor projecting the two light beams onto the same area of an appropriate screen; a plurality of sets of slides, there being two slides for each set; a

magazine to hold all the slides, said magazine y having means deiining definite locations for the sets of slides; means for moving the magazine with an intermittent motion along a deiined path to successively bring each set of slides into a predetermined projection plane normal to the light beams; and means for simultaneously moving one set of slides in said plane from the carrier directly into projecting position across the light beams and for returning another set of slides from projecting position to the carrier.

5. In a projector, the kcombination of: means for producing two separate light beams; means for projecting the two light beams onto the same area of an appropriate screen; a plurality of sets of slides, there being two slides for each set; a magazine to hold all of the slides, said magazine having means for defining a definite location for each set of slides; a carriage movable linearly along a line substantially parallel with the light beams, said carriage being adapted to removably receive the magazine to advance the same therewith; means for moving the carriage in de nite steps to successively bring different sets of slides into a predetermined projection plane normal to both light beams; and means for simultaneously moving the slides of a set occupying said plane from the magazine into projecting positions across the light beams.

6. In a projector, the combination of: means for producing two separate light beams; means for projecting the two light beams onto the same area of an appropriate screen; a plurality of sets of slides, there being two slides for each set; a magazine to'hold all of the slides, said magazine each set of slides; a carriage movable linearly along a line substantially parallel with the light beams, said carriage being adapted to removably receive the magazine to advance the same therewith; means for moving the carriage in definite steps to successively bring different sets of slides into a predetermined projection plane normal to both light beams; and means for simultaneously moving .the slides of a set occupying said plane from the magazine into projecting positions across the light beams, and for effecting return of aset of slides lin projecting position to the magazine.

.7. In a projector having alight source and means for projecting a light beam `onto an appr'oprlate screen, the combination of: an open topped slide magazine adapted to hold a plurality of slides; a carriage movable along a defined linear path substantially parallel with the lightr beam, said carriage having means for removably receiving the magazine whereby the magazine travels with the carriage; and means for simultaneously lifting 'a slide out ofthe magazine into a projecting position across the light beam and for effecting the return of a shown slide back to the magazine.

8. In a projector having a light source and means for projecting a light beam onto an appropriate screen, the combination of: a carriage movable linearly along a dened path to carry a plurality of slide's`s`uccessively to a predetermined projection plane normal to the light beam; means for advancing the carriage with an intermittent step by step motion to successively bring the slides to said plane; means for simultaneously effecting transfer of a shown slide to the carriage an'd a slide to be shown in said' plane from the carriage to a projecting position across the light beam; and means for automatically uninterrupedly returning the carriage toits initial position after the last slide has been brought to projecting -position and returned to the carriage.

9. In a projector having a light source and means for projecting alight beam onto an appropriate screen, the combination of: a carriage movable linearly along a defined path to carry a plurality of slides successively to a predetermined projection plane normal to the light beam; means for advancing the carriage with an intermittent step by step motion to successively bring the slides to said plane; means for simultaneously return may be set to occur after any number of slides within the capacity of the carriage have` been shown.

10. In a projector of the character described: a slide carrier movable linearly along a defined I. path; means for intermittently advancing the carrier in one direction to successively carry slides thereon to a predtermined projecting plane including a clutch; electromagnetic means for engaging said clutch; mechanism for moving slides brought to said predetermined projection plane into projecting positions' with respect to a light source; means for uninterruptedly retracting' the carrier including another clutch; and

clutch actuating means for said other clutch rendered operative by advance of the carrier to a predetermined position to engage said last named clutch `and thereby automatically eiect retraction of the slide carrier.

11. In a projector of the character described: a slide carriage movable linearly along a defined path; means for intermittently advancing the carriage in one direction including a continuously driven clutch member; means for intermittently shifting `the clutch member in a direction to effect advance of the carriage in said direction; a spring loaded device for shifting said clutch member in the opposite direction to eil'ect uninterrupted return of the carriage; a trigger for releasing said spring loaded device; and a trip adjustably connected with the carriage to move therewith and actuate said trigger to release the spring loaded device at any predetermined point along the advance of the carriage.

12. In a projector of the character described: a slide carriage movable linearly along a dened path; means for intermittently advancing the slide carriage; means for uninterruptedly retracting the slide carriage; a control for initiating the functioning of said last named means including a trigger, and a trip movable with the carriage; and means for adjusting the position of the trip with relation to the carriage so that the point in the travel of the carriage at which the retracting means becomes effective may be adjusted..

13. In a, projector of the character described: a slide carriage movable linearly along a defined path between two extremes of motion; power driven mechanism for moving the carriage uninterruptedly in one direction to one of said extremes of motion; a control for said mechanism including a trigger; atrip for engaging the trigger; means slidably mounting the trip on the carriage for movement in Ya direction parallel with the carriage motion and in line with the trigger; and releasable means for securing the trip against longitudinal motion at any point along the length of the carriage.

-14. In a projector of the character described: a slide carriage movable linearly along a defined path between two extremes of motion; power driven mechanism for movingthe carriage uninterruptedly in one direction' to one of said extremes of motion; a control for said mechanism including a trigger; a trip for engaging the trigger; means slidably mounting kthe trip on the carriage for movement in a direction parallel with the carriage motion and in line with the trigger; releasable means for securing the trip against longitudinal motion at any point along the length of the carriage; and a scale carried by the carriage and delineated to correspond with the number of slides held by the carriage, said scale being positioned adjacent to the trip securing means to facilitate its adjustment.

15. In a projector of the character described:

a slide carriage movable linearly along a dened path; means for intermittently moving the carriage in one direction to advance the carriage; power driven means for moving the carriage uninterruptedly in the opposite direction so as to retract the carriage including a clutch member; a spring loaded device operable to move the clutch member to its operative position; a

^ trigger holding the spring loaded device potentially active; a vtrip movable with the carriage and engageable with the trigger to effect uninterrupted retraction ofthe carriage upon advance to a predetermined point; and means operable upon retraction of the carriage for moving the clutch member to inoperative position and reloading the spring device.

16. In a projector of the character described, the combination of: means for projecting slide units; a slide carrier having means dening pockets to readily removably hold a plurality of slide units in a row on the carrier with one slide unit in each pocket; means mounting the carrier for linear movement in opposite directions along a defined path in line with said row of slide units to enable advancing and retracting of the carrier; means for intermittently advancing the carrier to bring successive slide units to a. location from which they are movable into projecting position; means for effecting the transfer of slide units brought to said location during the'intermittent advance of the carrier out of said pockets to "projecting position and for returning projected slide units from projecting position back to said pockets; power driven means for uninterruptedly retracting the carrier; and means for effecting return of the last shown slide unit to the carrier before retraction of the carrier begins.

17. In a projector of the character described, the combination of: means for projecting slide units; a slide carrier movable linearly in' opposite directions; means on the slide carrier defining a succession of pockets to readily removably hold a plurality of slide units in a row extending in the direction of motion of the carrier and with one slide unit in each pocket; means for intermittently moving the carrier in one direction to successively present slide units to slide shifting mechanism; slide shifting mecheffecting return of the last shown slide unit to a 

